Is an 87 wranglers' axle compatible with a 95yj? (both are dana 35's) It's going to have 4.56 gears. Whereas I have 3.07. Would it be a straight swap or require modifications? What is the typical cost to expect for a gear swap in a front Dana 30?
Thanks In-Advance

It should be a straight swap. However, unless your getting a great deal, I would look for a d44 or better. The only benefit you'll gain with the 87 axle is the non c-clip axle shafts. Keep that in mind when/if your looking for a locker.

The gear swap should run around 300 if you know someone who can do the work for a reasonable cost. That cost includes the gear's, complete install kit, and shipping/tax.